Advanced Structural Mechanics
پیاپی 3 (Summer 2023)

In the concept of sensor and actuator applications, it is very interesting and important to sensing and actuating in small scales that now days has occupying a wide ranges engineering applications. Some of these sensors and actuators must work in the presence of other materials like fluids. In this paper, free vibration analysis of piezoelectric nanotube conveying fluid and resting on the visco-Pasternak foundation is performed. The displacement field is based on first-order shear deformation theory and also the modified couple stress theory is utilized for consideration of nanoscale size effects. The closed-form Navier solution is considered for simply supported piezoelectric fluid conveying nanotube and finally, the governing equations are derived according to the Hamilton principle. The results are compared with other results found in the literature and a good agreement is achieved. The effects of various parameters such as fluid velocity, size effect parameter, geometry of nanotube, and visco-Pasternak foundation on the natural frequency and damping of fluid conveying nanotube are investigated.

This research investigates the amount of energy absorption in a sandwich panel with a corrugated core of an egg comb with two different dimensions. Sandwich panels with different core shapes are widely used in the transportation industry due to their lightweight, and many studies have been conducted on their properties, one of which is the study of energy absorption. Investigating the amount of energy absorption in these types of cores will help to increase the safety of the passengers. In this research, the cores with the ratio of the angle of the leg to the base of 30 degrees (T30) and 40 degrees (T40) were made through sheet cutting and bending and were connected to each other using spot welding. ST 37 steel sheet was used for the core and surface. The samples were subjected to a quasi-static uniform load. The force-displacement curves were obtained and the peak force value, energy absorption rate, specific energy absorption, and energy absorption efficiency were calculated from the crushing behavior of the sample. It was found that the angle ratio has an effect on the amount of energy absorption. The amount of energy absorption in T40 was about 1.5 times that of the T30 model.

In this research‚ the studies about the behavior of contact mechanics among other surfaces have been presented according to the statistical functions. Also‚ with the knowledge of the statistical parameters of roughness‚ the certain area roughness of the studied surfaces has been predicted by using a Gaussian statistical function. The obtained data is the base of defining the geometry of the surfaces which contacts together. As a matter of fact, by modelling the surface geometry‚ the mechanical behavior of the two contacted surfaces have been calculated in two different conditions as follows: loading conditions of 500 and 5000 micro-Newton’s by finite element method. The elastic and plastic behavior of the involved surfaces are investigated under two loading conditions and have been considered in detail. At some point‚ examples such as the quality of contact surfaces in the macroscopic scope‚ contact area‚ the height of vertices‚ and weight function are discussed. The result showed that the roughness of the surface is undesirable‚ but it is a stress-intensifying factor. Regarding the statistical characteristics of the roots-mean-square‚ it can be found that the shrinkage of the roots-mean-square of the surface leads to the decline in the height of the vertices in the surface which‚ in turn‚ results in a decrease in contact stress.

The use of steel braces in the structure is the most practical method to increase the lateral stiffness of the building. Nowadays, all kinds of modern braces are used in the structure. Gate and Inverted V braces are very common and modern. In the present paper, using ABAQUS software and Finite Element Method (FEM), Gate and Inverted V braces were modelled and compared. The material in the modelling is St37 type. In the present paper, the structures were analyzed in the frequency domain during modal analysis. The present paper was verified with the results of the paper by Mosalman et al. The results showed that the Inverted brace has lower von Mises stress (equal to 29.18% reduction) and displacement (equal to 16.69% reduction) compared to the Gate brace. Also, the Gated brace has a lower natural frequency (very low reduction) and eigenvalue (equal to 19.46% reduction) compared to the Inverted V brace.

The strength of a laser-welded steel corrugated sandwich panel with a circular opening at the center under compressive in-plane load is studied using finite element method. The opening is stiffened with a ring and the effect of the stiffening ring on the strength of the sandwich panel is assessed. Corrugated sandwich panels are structural components that have good mechanical behavior under the impact, bending, and in-plane loading. Thus, they are widely used in structures that operate in severe loading conditions such as marine and aerospace structures. The sandwich panel is modeled in Ansys software using shell elements and the welding connection between the faceplate and corrugated core is modeled with shell elements. The contact between the faceplate and corrugated core is defined as a frictionless contact, so the faceplate and core panel are both thin-walled structures that are free to buckle independently. It was deduced that the ring’s thickness can change the strength of the sandwich panel, but it does not increase the strength up to the strength of the intact plate. It was also found that the opening diameter can decrease the strength of the sandwich panel dramatically.

In this research article is investigated by experimental and analytical (FE modeling with ANSYS) for T welded joints under tensile test. The SEM and EDS methods were applied for failure surface of welded joint. 3D model of welded joint was developed by using ANSYS software and simulated. The deformation of welded joint model in ANSYS was validated by using performing experiment. The fractography study is carried out with the help of scanning electronic microscope (SEM) method. It is observed the brittle and ductile fracture surface at heat affected zone. The chemical composition was found using DSE method, the experimental outcomes represented that the T-joint is much stronger than the corner joint. ANSYS results are much closed to the experimental results. FE model is created by using SOLID187 elements. The stress sanguinity at junction of T-welded joint was studied. Stress singularity decreased with increasing load The systematical examine failure surface of welded joint by using SEM method T-type of welded joint is very stronger that other joint as, Butt, Lap and Corner joint. Failure load of present model is 30KN is suggested by designing the military aircraft structure.